Method of stabilizing sulfur and sulfur compounds in crude petroleum



Patented Nov. 18, 1.947

LIETHOD OF STABILIZING' AND- SULFUR, COMPQUNDS IN CRUDE PETBO- Charles0. Hoover, Houston, Tex, assignor to Air Reduction Company,Incorporated; New York,

No Drawing.

This invention relates to the fixation of sulfur in crude petroleum andparticularly to a method whereby the difficulty arising from thepresence of sulfur and its compounds is avoided. Crude petroleum.often'contains unstable inorganic and organic sulfur compounds, and mayalso contain 1 elemental sulfur and hydrogen sulfide.- The presence ofsulfur, in the forms in which it occurs naturally, often causes seriouscorrosion of tanks,

pumps and pipe lines. Also in the distillation of such crude petroleumthe distillates are contaminated with sulfur as hydrogen sulfide,mercaptans, and disulfides, which as a rule are formed as a result ofpyrolysis. These sulfur compounds are evolved as vapors during thedistillation, and

may be totally or partially condensed with the distillate. The heatexchange surfaces of the distillation equipment are subject to seriouscorrosionby the sulfur compounds, particularly by hydrogen sulfide andmercaptans.

Many attemptshave been made to neutralize sulfur compounds in crudepetroleum, but up to this time no noteworthy success has been achieved.See Qil and Gas Journal, June 24, 1943,

page 111, for summary of the-problem. As a 25 result, corrosion-oftransportation and distillation equipment continues, and the sourdistillates obtained from the crude petroleum contain sulfur which mustsubsequently be removed or modified before the distillates can be used.

It 'is the object of this invention to provide a method for the fixationof sulfur in crude petroleum, whereby the sulfur is converted to ,non-

corrosive forms and gives rise to products which do not containelemental sulfur, hydrogen sulfide, mercaptans or disulfides. Since thedistil lates are obtained free from elemental sulfur, hydrogen sulfide,mercaptans and disulfides, no subsequent treatment for the removal ormodl-. fication of these sulfur compounds is necessary.

Other objects and advantages of the invention will be apparent as itisbetter understood by reference to the following specification, inwhich the preferred embodiments are described.

I have. discovered that the introduction of cuprous naphthenate into thecrude oil at ordinary temperatures immediately produces relative- 1ystable and non-corrosive sulfur compounds.

I prefer to introduce cuprous naphthenate into the crude oil assoon aspossible after the deliv-' ery of the oil from the oil well. The oil maythen be transported or stored with little or no damage. to tanks, pumps,pipelines, etc. It may be distilled in any suitable distillationequipment without the hazard or the corrosion which attends N. Y., acorporation of New York Application February 1, 1945, Serial No. 515,140

OClalma. (Cl. 196-30) the distillation of 011 containing unstabilizedsulfur compounds.

Cuprous naphthenate may be prepared in any convenient way as, forexample, from cupric I naphthenate by reduction, and may be utilized inany convenient form. Since cuprous naphthenate is easily oxidized, itmust be protected from the atmosphere. I prefer to use a solution ofcuprous naphthenate in oil and to add the solution to 10 the crudepetroleum. The amount ofcuprous naphthenate required will vary dependingon the nature of the crude oil to be processed. The

various types of sulfur compounds which may be present in crude oilsoccur in widely varying ratio. For this reason it is-not always possibleto predict the proper dosage from analytical data alone. I prefer todetermine the dosage by actual test. As little as 0.1% by weight isoften effec-.

tive. One per cent or more may be used, though larger amountsare rarelyrequired.

For example, I have stabilized a Carnie crude by the addition of 0.1% byweight of cuprous naphthenate. Subsequent distillation gave gasoline andkerosene fractions free from hydrogen sulfide, mercaptans anddisulfides. In this case,

the amount of cuprous naphthenate added to the crude was equivalent toonly a small fraction of the-total sulfur present. Nevertheless the sul-I" fur and sulfur compounds were substantially stabilized. v Without theaddition of the cuprous naphthenate to this crude oil, the distillatesobtained were contaminated with elemental sulphur, hydrogen sulfide,mercaptans and disul. tides and required further treatment to be madesuitable, for commercial use. I have obtained 1 equally good results bytreating other crudes. with an appropriate amount of cuprousnaphthenate.

In the event thatthe crude 011 contains hydrogen sulfide, the use ofcuprous naphthenate is particularly advantageous, since it reacts withthe hydrogen sulfide to form cuprous sulfide. Cuprous sulfide does notreadily decompose at.

' distillation temperatures to form elemental sulfur, whereas cupricsulfide will decompose under such conditions with the formation ofelemental sulfur. The latter readily reacts with hot hydrocarbons toform hydrogen sulfide. Mercaptans and disulfides may also be formedunder such conditions and will appear in the distillates unlesssteps'are taken to ensure their elimination.

For the purposes of this invention the term "stable sulfur compoun is.considered to be a non-corrosive sulfur compound which under the asconditions of distillation of thecrude petroleum,

. 3 does not decompose to give hydrogen sulfide. mercaptans or disulndesin the distillate. 7

While cuprous naphthenate is the preferred reagent in the method, otherlower valence copper compounds such as the oleate, linoleate', stear;

ate, resinate, and acetate may be employed in a similar manner with likeresults. It is essential to avoidthe cupric compounds which donot affordthe advantages of the present invention.

The invention as described aifords a simple and economical solution ofthe problems arising from the presence of sulfur andsulfur compounds incrude petroleum. Various changes may be made in the details of procedurewithout departing from the invention or sacriflcingthe advantagesthereof.

I claim:

1. The method of stabilizing. sulfur and sulfurcompounds in crudepetroleum -which comprises adding an oil soluble cuprous compound, inprothe'crude in amount sufllcient to convert the unstable sulfurcompounds in the crude into stable sulfur compounds, and thereafterdistilling the crude to obtain distillates substantially free fromhydrogen sulfide. mercaptans, disulflde's and elemental sulfur. f

4. The-method of stabilizing sulfur and sulfur portion sufficient toconvert the unstable sulfur compounds into stable sulfur compounds, tothe crude petroleum at prevailing atmospheric temperature. a

5. The method of stabilizing'sulfur and sulfur compoundsin crudepetroleum which comprises adding cuprous naphthenate, in proportion ofonly a fraction of the amount equivalent to the sulfur present in thecrude petroleum and sufflcient to convert the unstable sulfur compoundsinto stable compounds, to the crude petroleum.

6. The method of stabilizing sulfur and sulfur compounds in crudepetroleumwhich comprises adding cuprous naphthenate. in Proportion ofonly a fraction of the amount equivalent to the sulfur present in thecrude petroleum and sufflcient to convert the unstable sulfur compoundsinto stable co'mpounds,-to the crude petroleum,

at the prevailing atmospheric temperature.

" CHARLES o. noovma.

ltEFERENCES crrnn The following references are of record in the flle ofthis patent:

\ UNITED STATES PATENTS

